Yes and no. This is a common pattern, but implemented very lazily. Most of this can (and probably should) be refactored out to separate classes/functions.
But no, I don't think this would faze most Java devs. It's ugly and bad practice, but more or less acceptable depending on personal taste. It works, at least.
Point of interest: LLMs tend to go too far in the opposite direction with code like this. They will break everything apart into functions or classes, even trivial one-line lambdas. I find that even more obnoxious than the monstrosity you linked.
But no, I don't think this would faze most Java devs. It's ugly and bad practice, but more or less acceptable depending on personal taste. It works, at least.
Point of interest: LLMs tend to go too far in the opposite direction with code like this. They will break everything apart into functions or classes, even trivial one-line lambdas. I find that even more obnoxious than the monstrosity you linked.